Device for preventing unauthorized use of an engine

ABSTRACT

The invention relates to a device (1) for preventing unauthorized use of an engine provided with a spark plug, from which the ignition cable has been removed and conditions have been provided which will enable the spark plug to be covered and therewith made irremovable, or at least not readily removable. The device includes a sleeve (6) which can be fitted over a spark plug (2) to which no ignition cable is connected, and a spark-plug coacting locking part (4, 5). The sleeve (6) and the locking part can be locked in a position relative to one another or in a position in which they are able to move relative to one another, through the medium of a locking device (7). The locking part (4, 5) which coacts with the spark plug (2) can be moved relative to the sleeve (6) in a direction pertinent to a sleeve center line (6a), from a position in which it is located outside the sleeve and in which the spark plug (2) is exposed or can be embraced by the sleeve, to a position inside the sleeve (6) in which the spark plug is embraced and in which the locking part (4, 5) is able to rotate freely around the cylindrical base part (2a) of the enclosed spark plug.

TECHNICAL FIELD

The present invention relates to a device for preventing unauthorizeduse of an engine provided with spark plugs, and particularly, but notexclusively, to devices of the kind with which it is necessary todisconnect the ignition cable from a spark plug and then createconditions which enable the spark plug to be covered by the device in amanner which will prevent the device from being readily removed from thespark plug.

The invention is based on a device which includes a sleeve which can befitted over a spark plug when the ignition cable has been removedtherefrom and which has a locking part which coacts with the spark plug,wherein the sleeve and said locking part can be locked in mutualrelative positions or can be positioned so as to be movable relative toone another.

Although the invention can be applied with different types of engines,it finds particular use in preventing the theft of motorcycles, snowscooters and like vehicles, or at least making such theft difficult toachieve.

DESCRIPTION OF THE PRIOR ART

Swedish Patent Application 7606432-8, Publication No. 404,159, teaches amethod and a device for preventing unauthorized use of internalcombustion vehicles, ships, engine-driven tools and implements, andsimply engines or motors, and is based on the removal of spark plugsfrom an engine and replacing the spark plugs with a body which has anexternal screw-thread which corresponds to a spark plug housingattachment and which is rotatably or pivotally connected to asleeve-like part which extends from the engine block and intended toencircle a locking mechanism.

The locking mechanism can be brought by means of a key to a position inwhich it joins the screw-threaded part non-rotatably to the sleeve-likepart when mounting the body on and removing said body from the engineblock, wherein the locking mechanism is also adapted to be brought, withthe aid of said key, to a position in which the sleeve-like partextending from the engine block is able to rotate freely in relation tothe threaded attachment part and therewith make it impossible to removethe body from a position in which it is attached to the engine block.

Swedish Patent Application 7714838-5, publication No. 413,046, teaches acorresponding device referred to as a spark plug lock, which is intendedto improve the construction described in the introduction, by using alocking device which does not require removal of the spark plug.However, this construction requires the provision of a separate holderwhich is fitted between the spark plug and the engine block.

This known device includes an outer cylindrical housing which isintended to embrace a key-operated lock mechanism and a sleeve-likerotor which coacts with the housing and is enclosed within said housingand which, with the aid of the lock mechanism, can be caused to locknon-rotatably with the housing and to be arranged for rotation inrelation to the housing respectively.

The rotor interior includes a space for receiving the isolator of aspark plug and ignition line connection means.

The rotor is provided at its bottom end with an internal screw-threadwhich is intended to mesh with an external screw-thread on a cylindricalholder, this holder including an upper hexagonal recess which isintended to receive a hexagonal spark plug, and therebeneath acylindrical space which receives the cylindrical base part of the sparkplug, wherein the height or vertical extension of the holder is such asto enable a spark plug with the holder fitted thereto to be screwed intothe engine block in a normal manner.

DISCLOSE OF THE INVENTION TECHNICAL PROBLEMS

When studying the present state of the art as described above, it willbe seen that a technical problem resides in providing a lockingdevice/particularly a spark plug locking device, which is constructed soas to enable it to be brought into and out of coaction with a spark plugwithout needing to fit additional devices, such as a holder, to thespark plug.

Another technical problem with regard to a locking device of theaforedescribed kind is one of providing conditions which will enable thelocking device to lock and to release the spark plug, simply by enablinga sleeve and a part of the locking device to lock together in a positionof mutual orientation or to be movable relative to one another in adirection pertinent to a centre line on the sleeve.

It will also be seen that a technical problem is one of realizing theadvantages that are afforded by enabling a locking part that coacts withthe spark plug to be movable in a direction pertinent to a centre lineon the sleeve in relation to said sleeve from a sleeve-externalposition, in which the spark plug is located outside the sleeve and canbe embraced thereby, to a position in which the spark plug is enclosedwithin the sleeve and in which said locking part is able to rotatefreely around the enclosed spark plug and thus around the bottomcylindrical base part thereof.

It will also be seen that another technical problem is one of realizingthe significance of providing said locking part with shoulders or lugsthat can be inserted to and withdrawn from a position beneath thehexagonal collar of the spark plug, and the movement of which shouldersis controlled by relative displacement between said locking part andsaid sleeve, so as to be enclosed in their inserted position and heldfirmly adjacent the spark plug while enabling relative movement inrelation to the spark plug.

It will also be seen that another technical problem is one of realizingthe significance of biassing said part towards and to a position outsidethe sleeve with the aid of a spring, and also in providing aspring-accommodating space within a cylindrical part or sleeve.

It will also be seen that a technical problem is one of realizing theadvantages that are afforded by enabling said locking part to be lockedto said sleeve by means of the locking device, solely when locatedwithin the sleeve.

Another technical problem is one of realizing the significance offorming said locking part from two diametrically opposed arm-likelocking or gripping elements which can be displaced and/or deflectedtowards and away from one another through the medium of saiddisplacement and spring bias.

A further technical problem is one of realizing the advantages that areafforded when the locking device includes a spring-activated disc orplate which is able to rotate under a spring force to a position inwhich said locking part is locked in relation to the sleeve in the innerposition relative to the sleeve, and when the plate or disc can beturned by the key of said locking device against the force of a springand therewith release said part from the sleeve.

Another technical problem is one of realizing the advantages that areafforded when each of the locking elements is provided with anindividual, obliquely downwardly directed projection against which aspring rests, and by directing the spring force such as to bring saidlocking elements into an outwardly directed position when said elementsare not in contact with the sleeve.

It will also be seen that a technical problem is one of realizing thatthe sleeve shall have a circular cross-section and that the aforesaidlocking elements, in their outwardly directed position, are latchedagainst coaction with opposing inner surface parts of the sleeve.

It will also be seen that a technical problem resides in realizing thesignificance of, and the advantages that are afforded when attaching theinventive device to a spark plug, of providing the sleeve with anarrower part, a spark plug encircling part, and a broader part, alocking device encircling part.

Another technical problem is one of realizing the significance ofpositioning said disc or plate adjacent the narrower part and adjacentthe broader part within the sleeve, which has a circular cross-section,and causing the disc or plate to be pressed against inner parts of saidpart by a spring force.

SOLUTION

With the intention of solving one or more of the aforesaid technicalproblems, the present invention is based on a device for preventingunauthorized use of an engine provided with spark plugs and/orunauthorized use of the vehicle in which the engine is fitted, byremoving the spark plug ignition cable and thereafter creatingconditions which will enable a spark plug to be covered by the deviceand which will prevent removal of the device, or at least render removaldifficult, wherein the device comprises a sleeve which can be fittedover and around a spark plug when the ignition cable has been removedand which has a part which coacts with the spark plug, wherein thesleeve and said part can be locked in mutual positions by means of alocking device or can be allowed to move relative to one another in afree, unlocked state.

According to the invention, the part that coacts with the spark plug canbe moved relative to the sleeve in a direction of a sleeve centre line,from a position outside the sleeve in which the spark plug is exposed orcan be embraced by the sleeve, to a position in which it is locatedinside the sleeve with the spark plug enclosed thereby, wherein saidpart can be freely rotated around the bottom cylindrical part of theenclosed spark plug, by means of mutually opposing shoulders.

According to preferred embodiments lying within the scope of theinventive concept, said part includes shoulders or lugs which can bebrought into and out of abutment with the bottom cylindrical part of thespark plug, so that when inserted they encircle or embrace thecylindrical part of said spark plug at a location beneath a hexagonalportion thereof.

Preferably, said part will be spring-biassed towards a position locatedoutside the sleeve.

When using the locking device, the aforesaid part will preferably becapable of being locked automatically to the sleeve in a position withinsaid sleeve.

The aforesaid locking part includes two diametrically opposed,elongated, arm-like locking elements of which those portions that facetowards the spark plug can be curved or displaced towards and away fromone another as they are moved.

The locking device will also preferably include a spring-biassed disc orplate which is able to rotate to a part-locking position in relation tothe sleeve in the internal position relative thereto, and which uponmanipulation of a key belonging to the locking device can be turned backto release said part from the sleeve against the action of a spring.

Each of the aforesaid locking elements is provided with an obliquelydownward extending projection which coacts with a spring unit andagainst which the ends of the spring rest, such as to move the lockingelements to an outwardly directed position by the force of the springwhen said locking part and the sleeve are separated from one another.

When in their outwardly directed position, the locking elements arelatched against coaction with opposing inner sleeve surfaces.

It is also proposed that the sleeve is provided with a narrower,spark-plug embracing part, and a broader, locking-device embracing part,and that said disc or plate is located adjacent the narrower part andalso adjacent the broader sleeve-part, said sleeve having a circularcross-section.

ADVANTAGES

Those advantages primarily afforded by the invention reside in theprovisions of conditions whereby a spark plug can be locked solely byplacing two locking elements, inserted in a sleeve-like part, over thespark plug and thereafter pressing the sleeve-like part over saidlocking elements against a spring force, therewith bending or flexingsaid locking elements in against the cylindrical base part of the sparkplug in locking coaction therewith.

When the locking elements and the sleeve of the locking device are in alocking position, the locking elements are able to rotate around thespark plug and prevent its removal from the engine block.

The locking device enables the locking coaction between the lockingelements and the sleeve to be deactivated, by moving the sleeve awayfrom the spark plug against the force of a spring, so that the lockingelements will expand and therewith enable the locking device to beremoved from the spark plug.

The primary characteristic features of a device for preventingunauthorized use of an engine provided with spark plugs in accordancewith the present invention are set forth in the characterizing clause ofthe following claim 1.

BRIEF DESCRIPTION OF THE DRAWING

An exemplifying embodiment of an inventive locking device at presentpreferred will now be described in more detail with reference to theaccompanying drawing, in which

FIG. 1 is a perspective view of an inventive locking device in aninactive position, immediately prior to its coaction with a spark plug;

FIG. 2 illustrates the locking device in an active and locking state inwhich the device coacts with the spark plug, although the spark plug hasnot been shown for the sake of simplicity;

FIG. 3 is a perspective view of the locking device from above;

FIG. 4 is a cross-sectional view of the locking device according to FIG.2 and in broken lines according to FIG. 1;

FIGS. 5 and 6 are different projection views of one of two partsfunctioning as gripping means;

FIG. 7 is an end view of the part shown in FIG. 6;

FIG. 8 is a side view of a spacer sleeve for coaction with the lockingdevice;

FIG. 9 is a side view of a locking-device turning means; and

FIG. 10 is a horizontal view of the turning means shown in FIG. 9.

DESCRIPTION OF EMBODIMENTS AT PRESENT PREFERRED

The present invention relates to a device 1 for preventing unauthorizeduse of an engine fitted with a spark plug 2.

The use of the device is contingent on the removal of an ignition cablefrom the spark plug 2 with the plug screwed firmly in the engine blockas illustrated in FIG. 2.

Initially, the device 1 has the inactive state shown in FIG. 1 and ismoved in the direction of arrow P to embrace the spark plug 2. In sodoing, two locking elements 4, 5 movably mounted in a sleeve 6 arecaused to embrace the spark plug 2 such that surfaces 4a, 5a on thelocking elements will be caused to coact with a surface 3a of the engineblock 3 located adjacent the spark plug 2.

The sleeve 6 is now pressed further down towards the block surface 3a,causing the locking elements 4 and 5 to be pressed towards one another,so that inwardly facing shoulders 4b, 5b will embrace a cylindrical basepart 2a of the spark plug 2 located beneath a hexagonal section 2b andthe top surface 3a of the block 3.

When in their innermost position, the shoulders 4b and 5b lie againstthe cylindrical base part 2a of the spark plug with a certain clearancein relation thereto, so that the sleeve 6 is able to rotate freelyaround said base part 2a.

The locking elements 4 and 5 can be locked relative to the sleeve 6 inthe position shown in FIG. 2 with the aid of a locking device 7, therebypreventing the device 1 from being removed from the spark plug 2 bymoving the device in a direction opposite to the illustrated directionP.

The locking part that coacts with the spark plug 2 and which iscomprised of said two locking or gripping elements 4, 5, can be moved ina direction of a sleeve centre line 6a relative to the sleeve 6 from aposition outside the sleeve, in which the spark plug is exposed or canbe embraced by the sleeve, as shown in FIG. 1, to a position in which itis located inside the sleeve and embraces the spark plug 2, as shown inFIG. 2. As a result of the dimensions and the coaction of the shoulders4b, 5b, the locking elements 4, 5 are able to rotate freely around thecylindrical base part 2a of the enclosed spark plug.

As will be understood, the shoulders 4b and 5b have a vertical extensionor height which will enable the lower part of the sleeve 6 and a springto bring the shoulders into and out of engagement with a hexagonalsection 2b of the spark plug, wherein the shoulders will have a formwhich causes them to embrace partially the section 2a of the spark plugin an engaged position.

FIG. 4 is a cross-sectional view of the device when in the positionshown in FIG. 2, wherein the sleeve 6 and its bottom part 6" enclose thelocking elements 4, 5, which are mutually identical and a mirror imageof one another.

The locking elements 4, 5 are spring-biassed by means of a spring 10towards a position outside the sleeve 6, shown in broken lines in FIG.4, FIG. 4 therefore showing said parts in a compressed state.

The locking device 7 coacts with a locking-part turning means 12 throughthe medium of a spacer 11, such as to lock the locking elements 4, 5 tothe sleeve 6 in a position inside the sleeve, through the medium of thelocking device 7 among other things, wherein the turning means 12includes a recess having a surface 12a which is intended for latchingcoaction with a surface 5c.

The turning means 12 also includes a surface 12a' which is intended forcoaction with a corresponding surface 4c on the locking part 4,therewith effecting simultaneous locking and release of the two lockingelements 4 and 5 in relation to the sleeve 6.

The locking elements 4, 5 are comprised of two arm-shaped parts 4, 5which are diametrically opposed in relation to the sleeve 6 and thelower portions of which can be flexed or bent towards and away from oneanother as the device 1 is moved in respective directions.

To this end, the locking element 5 has a web portion 5d and an upperguide portion 5e, wherein the part 5' can be bent or moved from theposition shown in FIG. 4 to the position 5".

The locking elements 4 and 5 are thus bendable or movable towards andaway from each other in response to said movement.

The turning device with which the locking device 7 coacts has the formof a disc (12) provided with pins 12b, 12b' which coact with a spring(not shown), wherein the spring force is directed so as to cause thedisc 12 to rotate to a position in which the locking elements 4, 5 arelocked in relation to the sleeve 6 in their sleeve-internal position.The disc 12 can be turned back against the spring force with the aid ofa key 7' which fits the locking device 7, so as to loosen the lockingelements 4, 5 from the sleeve 6 and enabling the spring 10 to move saidelements 4, 5 to the position shown in FIG. 1.

Each of the locking elements 4, 5 is provided with an obliquely downwardprojection, which extends at an angle of about 15°, the projection ofthe locking element 5 being referenced 5f. The spring 10 rests againstthe projection 5f and the force exerted by the spring causes the lockingelements 4, 5 to take an outwardly directed position in which theelements 4, 5 and the sleeve 6 are mutually spaced apart.

When in their outwardly directed position, the locking elements 4, 5 arelatched in this expanded state through their coaction with the opposinginner edge-related or end-related inner surface parts 6a, 6b of thesleeve 6.

As shown in FIG. 4, the sleeve 6 has a bottom, narrower part 6" which isintended to enclose the locking elements 4, 5 which embrace the sparkplug, and an upper, broader part 6' which is intended to enclose thelocking device 7.

The disc 12 is located between the narrow part 6' and the broader part6".

FIGS. 5 and 6 illustrate the locking element 5 in two separateprojection views, while FIG. 7 is an end view of the locking element 5shown in FIG. 6, with the configuration of the shoulder 5b and itsattachment to the part 5' shown more clearly.

FIG. 8 illustrates a spacer part 11 having an upper part 11a whichcoacts with the locking device 7, and a lower part 11b which coacts withthe turning means 12, said turning means having a centre axis 12c andtwo projections 12b, 12'.

Through their coaction with a spring (not shown), the projections urgethe turning means 12 to a locking position and rest against the part 5euntil it can turn to locking coaction with the surfaces 4c and 5c.

FIG. 10 illustrates the turning means 12 from above.

It will be understood that the invention is not restricted to thedescribed and illustrated exemplifying embodiment thereof, and thatmodifications can be made within the scope of the inventive concept asdefined in the following claims.

I claim:
 1. A sparkplug locking device for preventing unauthorized useof an engine, the engine having a sparkplug, the sparkplug having aportion that is radially larger than adjacent portions of the sparkplug,the device comprising:a sleeve having an internal opening; a lockingpart, the locking part having radially movable shoulder portions, theshoulder portions extending inwardly toward a centerline of the lockingpart, the locking part being movable along an axis of the sleeve from afirst position in which the shoulder portions are disposed outside ofthe sleeve and define a first opening to a second position in which atleast part of the locking part is disposed inside of the internalopening of the sleeve and the shoulder portions define a second openingsmaller than the first opening; a locking device for locking the lockingpart to the sleeve when the locking part is disposed in the secondposition, the locking device including a spring-activated disc, thespring activated disc being rotatable by a key between a first discposition in which the locking part is locked relative to the sleeve whenthe locking part is disposed in the second position and a second discposition in which the locking part is released from the sleeve against aspring force; and a spring arrangement, the spring arrangement biasingthe locking part toward the first position, wherein, when the lockingpart is in the first position, the sparkplug is adapted to be receivedbetween the shoulders of the locking part such that the shoulders aredisposed beneath the radially larger portion of the sparkplug and, whenthe locking part is thereafter moved to the second position, theshoulders prevent axial movement of the shoulders to a position abovethe sparkplug, the sparkplug being rotatable relative to the lockingpart when the locking part is in the second position.
 2. A deviceaccording to claim 1, wherein the locking part includes twodiametrically opposed locking elements, the locking elements beingradially moved towards and away from one another when the locking partis moved to the second and the first positions of the locking part,respectively.
 3. A device according to claim 2, wherein each of thelocking elements includes a respective obliquely downwardly extendingprojection in contact with a spring of the spring arrangement, whereinthe spring urges the locking elements to an outwardly directed positionwhen the locking part is in the first position of the locking part.
 4. Adevice according to claim 3, wherein, when the locking elements are inthe outwardly directed position, the locking elements are latched bycoaction with opposing internal surfaces of the sleeve.
 5. A deviceaccording to claim 1, wherein the sleeve includes a narrow spark-plugembracing part and a broader locking-device embracing part.
 6. A deviceaccording to claim 5, wherein the disc of the locking device is locatedadjacent to the narrow part of the sleeve and adjacent the broad part ofthe sleeve within the sleeve, the sleeve having a circularcross-section.
 7. A device as set forth in claim 1, wherein the shoulderportions are disposed at a first end of the locking part; and a portionof the locking part above the first end and the internal opening of thesleeve defining a space for receiving an extending portion of thesparkplug.